* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  user-select: none;
}
body {
  display: grid;
  place-items: center center;
  min-height: 100vh;
  background: #2196f3;
}
.loader {
  position: relative;
  display: grid;
  grid-auto-flow: column;
}
.loader span {
  width: 50px;
  height: 50px;
  margin: 0 20px;
  background: #f3ec21;
  border-radius: 50%;
  animation: loader 1.6s linear infinite;
}
@keyframes loader {
  0% {
    box-shadow: 0 0 0 rgba(0, 0, 0, 0.5);
    opacity: 0;
    transform: translateX(-50px) scale(1);
  }
  50% {
    /* 上下阴影 左右阴影 阴影模糊(可选) 阴影面积(可选) 阴影颜色(可选)  */
    box-shadow: 0 10px 50px rgba(0, 0, 0, 0.5);
    opacity: 1;
    transform: translateX(0) scale(1.2);
  }
  100% {
    box-shadow: 0 0 0 rgba(0, 0, 0, 0.5);
    opacity: 0;
    transform: translateX(50px) scale(1);
  }
}
.loader span:nth-child(1) {
  animation-delay: 0s;
}
.loader span:nth-child(2) {
  animation-delay: 0.2s;
}
.loader span:nth-child(3) {
  animation-delay: 0.4s;
}
.loader span:nth-child(4) {
  animation-delay: 0.6s;
}
.loader span:nth-child(5) {
  animation-delay: 0.8s;
}
.loader span:nth-child(6) {
  animation-delay: 1s;
}
.loader span:nth-child(7) {
  animation-delay: 1.2s;
}
